White sclera does make gaze direction visible, which could theoretically aid predators or rivals. However, this is outweighed by substantial social advantages. The cooperative eye hypothesis, supported by both members, explains why humans uniquely evolved prominent white sclera: it enables rapid gaze-following, facilitating non-verbal communication, collective hunting, and complex social bonding [1]. Most other primates retain dark sclera that camouflages their iris and gaze direction, prioritizing individual concealment.

Humans evolved white sclera because cooperation became more critical to survival than stealth. The ability to quickly read where others are looking improved group coordination, teaching, and trust—essential for our species' success. Rather than a weakness, white sclera represents a specialized adaptation for social intelligence. It may also have emerged as a byproduct of selection for reduced aggression and more cooperative social structures, not necessarily through direct selection for the trait itself.